1. Field of the Invention
The present invention relates to a cleaning system for cleaning a semiconductor wafer, and more particularly, to a cleaning system used to remove ink from the surface of a semiconductor wafer.
2. Description of the Prior Art
In integrated circuit industry, in order to make active devices on a semiconductor die function properly, ceramic or plastic packaging material is typically used to wrap and protect the semiconductor die. Before a wafer is sent for package, certain electrical property tests are performed first by a wafer manufacturer in order to ensure the quality of the wafer. But since the wafer manufacturer and the wafer packaging company are usually not located at the same factory, the wafer manufacturer usually uses ink to mark each defective die of each wafer, and the wafer packaging company will only package good dies when they receive such inked wafers.
The inking process is usually performed in an automatic testing procedure in the present semiconductor industry. The automatic testing procedure uses a testing program installed in a control unit to decide which die fails the electrical test and then uses ink to mark it. However, the testing machine used in such automatic testing procedure may sometimes become inaccurate or the testing program may use wrong testing parameters so that the marks inked by the testing machine are totally wrong. For example, the ink head may deviate from its normal position and marks on wrong dies
When such problems occur, the ink on the surface of the wafer as to be removed. Presently the ink on such a wafer is manually washed off using sponge and acetone. The acetone is used as a cleaning solution to dissolve the ink on the surface of a wafer and the sponge is used to manually scrub off the dissolved ink from the surface of the wafer. A lot of cleaning solution is wasted in such process because the operator has to use the solution to flush the surface of the wafer continually. Besides, such process is very time-consuming and unpleasant to the operator because of the exposure to the acetone. Its efficiency is very low and the manual force exerted to the surface of the wafer may easily cause serious damage to the wafer.
It is therefore a primary objective of the present invention to provide a cleaning system which can remove ink from the surface of a semiconductor wafer so as to solve the above mentioned problems.
In an embodiment of the present invention, the cleaning system comprises a first cleaning mode of operation, a second cleaning mode of operation and a drying mode of operation. The first cleaning mode of operation uses an N-Methyl-Pyrolidone (NMP) solution over which the wafer is submerged and spun to dissolve the ink on its surface. The second cleaning mode of operation spins the wafer and sprays a cleaning solution on the surface of the wafer. The drying mode of operation then removes the residue from the surface of the wafer by spinning the wafer and using a gas to blow the surface of the wafer.
It is advantage of the present invention that the present invention provides an automatic cleaning procedure to perform the ink cleaning process. The man power can be saved and wastes of cleaning solutions can also be reduced. Furthermore, the surface of each wafer can be cleaned in a much safer manner.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment which is illustrated in the various figures and drawings.